Chemical compound
Octabromodiphenyl ether (octaBDE, octa-BDE, OBDE, octa, octabromodiphenyl oxide, OBDPO) is a brominated flame retardant which belongs to the group of polybrominated diphenyl ethers (PBDEs).
Composition, uses, and production
Commercial octaBDE (also known as "Octabrom") is a technical mixture of different PBDE congeners having an average of 7.2 to 7.7 bromine atoms per molecule of diphenyl ether.[2] The predominant congeners in commercial octaBDE are those of heptabromodiphenyl ether and octaBDE.[2][3] The term octaBDE alone refers to isomers of octabromodiphenyl ether (PBDE congener numbers 194–205).[4]
Composition of commercial octaBDE [5]
| Structure
|
Congener
|
Name
|
Fraction
|
|
BDE-153
|
2,2′,4,4′,5,5′-hexa-
bromodiphenyl ether
|
0.15–8.7%
|
|
BDE-154
|
2,2′,4,4′,5,6′-hexa-
bromodiphenyl ether
|
0.04–1.1%
|
|
BDE-171
|
2,2′,3,3′,4,4′,6-hepta-
bromodiphenyl ether
|
0.17–1.8%
|
|
BDE-180
|
2,2′,3,4,4′,5,5′-hepta-
bromodiphenyl ether
|
n.d.–1.7%
|
|
BDE-183
|
2,2′,3,4,4′,5′,6-hepta-
bromodiphenyl ether
|
13–42%
|
|
BDE-196
|
2,2′,3,3′,4,4′,5,6′-octa-
bromodiphenyl ether
|
3.1–10.5%
|
|
BDE-197
|
2,2′,3,3′,4,4′,6,6′-octa-
bromodiphenyl ether
|
11–22%
|
|
BDE-203
|
2,2′,3,4,4′,5,5′,6-octa-
bromodiphenyl ether
|
4.4–8.1%
|
|
BDE-206
|
2,2′,3,3′,4,4′,5,5′,6-nona-
bromodiphenyl ether
|
1.4–7.7%
|
|
BDE-207
|
2,2′,3,3′,4,4′,5,6,6′-nona-
bromodiphenyl ether
|
11–12%
|
|
BDE-209
|
Deca-
bromodiphenyl ether
|
1.3–50%
|
Only congeners with more than 1% listed.
OctaBDE is used in conjunction with antimony trioxide as a flame retardant in the housings of electrical and electronic equipment, mainly in the plastic acrylonitrile butadiene styrene, but also in high impact polystyrene, polybutylene terephthalate and polyamides.[6] Typically 12–15% of the weight of the final product will consist of octaBDE.[6]
The annual demand worldwide was estimated as 3,790 tonnes in 2001, of which Asia accounted for 1,500 tonnes, the Americas 1,500 tonnes, and Europe 610 tonnes.[7] The United Nations Environment Programme reports "Since 2004, it [octaBDE] is no longer produced in the EU, USA and the Pacific Rim and there is no information that indicates it is being produced in developing countries."[3]
Environmental chemistry
OctaBDE is released by different processes into the environment, such as emissions from the manufacture of octaBDE-containing products and from the products themselves.[3] Elevated concentrations can be found in air, water, soil, food, sediment, sludge, and dust.[3][8][9]
In the environment, "photolysis, anaerobic degradation and metabolism in biota" can cause debromination of octaBDE, which produces PBDEs with fewer bromine atoms "which may have higher toxicity and bioaccumulation potential."[3]
Exposures and health effects
OctaBDE may enter the body by ingestion or inhalation.[4] It is "stored mainly in body fat" and may stay in the body for years.[4] In an investigation carried out by the WWF, "the brominated flame retardant chemical (PBDE 153), which is a component of the penta- and octa- brominated diphenyl ether flame retardant products" was found in all blood samples of 14 ministers of health and environment of 13 European Union countries.[10]
The chemical has no proven health effects in humans; however, based on animal experiments, octaBDE may have effects on "the liver, thyroid, and neurobehavioral development."[4]
Governmental actions
The European Union has carried out a comprehensive risk assessment under the Existing Substances Regulation 793/93/EEC.[6] As a consequence, the EU has banned the use of octaBDE since 2004.[11]
In the United States, as of 2005, "no new manufacture or import of" pentaBDE and octaBDE "can occur... without first being subject to EPA [i.e., United States Environmental Protection Agency ] evaluation."[12] As of mid-2007, a total of eleven states in the U.S. had banned octaBDE.[13]
In May 2009, commercial octaBDE was added to the Stockholm Convention as it meets the criteria for the so-called persistent organic pollutants of persistence, bioaccumulation and toxicity.
Alternatives
Alternatives to octaBDE include tetrabromobisphenol A, 1,2-bis (pentabromophenoxy) ethane, 1,2-bis(tribromophenoxy)ethane, triphenyl phosphate, resorcinol bis(diphenylphosphate), and brominated polystyrene; however, for each of these "the existing data on toxicological and ecotoxicological effects are fewer than for octabromodiphenyl ether."[14]
